End cap for impregnating wood especially sap-fresh bark-covered tree trunks against rot and insects

ABSTRACT

AN END CAP FOR IMPREGNATING WOOD, ESPECIALLY A BARKCOVERED SAP-FRESH TREE TRUNK, HAVING A RIGID SECTION WITH PROVISIONS FOR CONNECTING A SOURCE OF WOOD-IMPREGNATING SOLUTION THERETO AND AN ELASTIC SECTION WHICH FORMS A LIQUID-TIGHT CHAMBER BETWEEN THE RIGID SECTION AND THE TREE TRUNK.

" E GJERSONDE ETAL 3582260 v I SAP-FRESH END CAP FOR IMPREGNATING WOOD ESPECIALLY i E 1, BARK-COVERED TREE TRUNKS AGAINST HOT AND INSECTS Filed May's, 1968 I v 2 Sheets-Sheet 1 In ventor's,

A /pr SfZZW/g J June M. GERS ONDE ETAL 3,532,260

END CAP FOR IHPREGNATING WOOD ESPECIALLY SAP-FRESH BARK-COVERED TREE TRUNKS AGAINST RQT AND INSECTS Filed mai s, 1968 I I 2 Sheets-Sheet z In ventars,

United States Patent Oflice 3,582,260 Patented June 1,, 1971 3,582,260 END CAP FOR IMPREGNATING WOOD ESPECIAL- LY SAP-FRESH BARK-COVERED TREE TRUNKS AGAINST ROT AND INSECTS Martin Gersonde, Christoph Kottlors, and Fritz Schwartz, Berlin, Germany, assignors to Dr. Wolman G.m.b.H., Baden, Germany Filed May 3, 1968, Ser. No. 726,459 Claims priority, application Germany, May 19, 1967, G 50,127; Dec. 20, 1967, G 38,611 Int. Cl. B271; 3/10 U.S. Cl. 21-71 12 Claims ABSTRACT OF THE DISCLOSURE An end cap for impregnating wood, especially a barkcovered sap-fresh tree trunk, having a rigid section with provisions for connecting a source of wood-impregnating solution thereto and an elastic section which forms a liquid-tight chamber between the rigid section and the tree trunk.

The present invention relates to a method of and device for impregnating wood, especially sap-fresh bark-covered tree trunks, by means of a chemical wood protective against rot and insects.

It is known by the employment of so-called impregnating caps applied to one or both trunk ends to force wood protective solutions under pressure into the barkcovered wood or under pressure and vacuum or only vacuum into the debarked sap-fresh wood. In the firstmentioned instance, a so-called pressure cap is placed upon one trunk end, and the protective solution is pressed by means of the latter pressure cap against the end face of the trunk end. With the impregnation of debarked wood in troughs filled with wood protective solutions, when employing pressure or vacuum, in addition to the pressure cap as mentioned, also a suction cap is placed on the other end of the trunk, and the said suction cap is hooked up to a suction pump. If it is desired to work only with a vacuum, only the suction cap at one end of the trunk is employed whereas no pressure cap is used.

These heretofore known methods have the drawback that the impregnating periods which require from fortyeight hours to ten days and more, are too long. Furthermore, the impregnation itself is not satisfactory and in particular, no additional or separate impregnation of those areas is obtained which are particularly exposed to dangers such as rot and insects. Such areas are, for instance, the portions of poles which are to be lowered into the ground. These drawbacks are primarily due to the fact that the pressure drop between the two trunk ends when injecting the wood protective solution is rela tively low, and the heretofore known impregnating caps cannot bring about that the wood protective solution is effectively and quickly distributed over the total impregnated area. This faulty manner of operation is brought about by misconception due to the erroneous belief that the fed quantity of liquid is not proportional to the pressure of the solution and that by increasing the vacuum at one end of the trunk, no increase in the impregnating speed and the control of the wood protective solution is obtained. These erroneous beliefs are based on tests of the trough-pressure-suction method from which false conclusions have been drawn.

It is, therefore, an object of the present invention to provide a method of and device for impregnating wood, which will overcome the above-mentioned drawbacks.

It is another object of this invention to provide a method of impregnating wood against rot and insects, which will greatly reduce the heretofore necessary time for carrying out such impregnating operations on tree trunks and the like.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

FIG. 1 illustrates a longitudinal section of a portion of a cap adapted to be used as pressurecap and as suction cap placed upon one end portion of a tree trunk; and

FIG. 2 is a longitudinal section through a one-wall suction cap according to the invention and shows the cap on the left-hand side without being placed on a tree trunk end, while the right-hand portion is placed on a portion of a tree trunk end.

FIG. 3 is a fragmentary sectioned view supplementing that of FIG. 1 and to show interrelationship of elements more clearly.

The present invention is based on the finding that, contrary to the heretofore prevailing opinion, the impregnating operation can be carried out at a higher fluid pressure and that, furthermore, the flow velocity of a liquid or gaseous medium, in addition to its viscosity and turbulence, depends primarily on the pressure drop to which the medium is subjected. Thus, with tree trunks which still have their bark, it is possible by increasing the pressure drop or pressure difference between the two ends of a trunk to increase the flow velocity of the protective solution in the trunk and thereby the impregnating speed, which in turn results in a considerable reduction in the time necessary for the desired impregnation.

Furthermore, it has been found, according to the invention, that the impregnation is complete only when the total impregnable wood of the cross-sectional surface of the trunk is served by the impregnating cap.

On the basis of the above findings, the objects underlying the present invention have been realized in con formity with the present invention by pressing the wood protective solution into the wood by means of an impregnating cap surrounding one trunk end and sealingly engaging the peripheral surface of the trunk, at a pressure of at least 29 pounds per square inch or 2 kp./cm. and more over the total end face of the respective trunk end. kp. is a conventional abbreviation for kilopond. A definition of weight unity of one pond equals 980,665 dyn. This results in a corresponding pressure difference between the two trunk ends when one trunk end is under atmospheric pressure and the wood protective solution is pressed over a pressure cap forming impregnating cap at a pressure of 2 l p./cm. or more against the trunk end face underneath said cap.

When in addition to providing the pressure cap at one end of the trunk, a suction cap connected to a suction pump is arranged on the other end of the trunk, it is possible further to increase the pressure difference. The said suction cap preferably consists of a rigid hood portion placed over the trunk end, and a sealing cuff or sleeve sealingly engaging the mantle surface or peripheral surface of the respective trunk end. If desired, also a suction cap only may be provided without the application of a pressure cap.

The pressure cap for carrying out the method according to the present invention consists primarily of a rigid hood having a diameter which corresponds at least to the outer diameter of the respective tree trunk end, and furthermore comprises a sealing sleeve which is detachably connected to said hood and engages the circumferential surface of the trunk end. The said sealing sleeve or cuff may, according to the present invention be designed in the form of a double-wall hose section with U-shaped longitudinal section of the wall, and is made of rubber with fabric threads or fabric inserts therein. The fabric threads inthe individual walls do not cross each other and in both walls have the same inclination with regard to the longitudinal central axis of the sleeve or cufi.

' For purposes of sealing, the U-shaped intermediate space between the double walis is charged with a liquid or gaseous pressure medium whereby the sleeve or cuff is stretched, and in addition, is pressed in a sealing manner against the circumference of the trunk end.

For purposes of aiding the sealing effect, the sleeve or cuff is according to a further development of the present invention reinforced at its tower end or at the zenith curvature of the U-shaped longitudinal cross section. The reinforcement is effected by a cross-wise overlapping of the fabric threads of the outer and inner walls of the sleeve at the lower sleeve end or at the zenith curvature. The reinforcement may also be effected by vulcanizing an additional fabric strip into the zenith curvature of the said U-shaped longitudinal section or by thickening the rubber at this area. For additionally aiding in the sealing effect, the sleeve or cuff may be so dimensioned that it will engage the circumference of the trunk end under a preload.

A protective sleeve of form-retaining material is then placed over the said cuif or sleeve.

The suction cap for carrying out the method according to the present invention comprises a rigid cap section and a one-wall sealing sleeve of elastic material, especially rubber, which may contain fabric threads or a fabric in sert, said one-wall sealing sleeve being preferably detachably connected to the rigid cap portion. The rigid cap portion is so dimensioned that it surrounds the trunk end, Whereas the inner diameter of the sealing sleeve is less than the outer diameter of the trunk end, so that the said cuff or sleeve will under load engage the circumferential surface of the trunk end.

According to a preferred feature of the present invention, between the circumference of the trunk end and the inner side of the mouth of the rigid cap portion extending over said trunk end, there is provided such a large intermediate space that through the evacuation step the upper portion of the said cuff or sleeve is drawn by the suction effect in a U-shaped manner into said space whereby the upper portion of said cuff or sleeve will bring into sealing engagement one leg of the now U-shaped portion with the circumference of the trunk end, whereas the other leg will sealingly engage the inner side of the mouth of the cap portion. That portion of the sealing sleeve which is located below the U-shaped portion will under preload and due to the suction sealingly engage the circumference of the trunk.

In cases where increased protection of areas of the trunk is desired, which areas are especially exposed to danger as, for instance, the trunk end to be lowered into the soil, it is suggested, according to the present invention,

uring or after sufficient impregnation for a full impregnation of the trunk, to press a further protective solution of a higher concentration and/or a different type under a higher pressure against the end face of the trunk end while a vacuum may be applied to the other end of the trunk. The time during which the protective solution is to be fed into the trunk is determined by the length of the trunk end which is to be impregnated particularly, by the pressure drop, the type of wood, and the condition and properties of the solution which by means of the impregnation cap or cuffs according to the invention, is to be pressed into the tree trunk. The operation may be carried out under the same pressure conditions as is the case with full impregnation or aiso at higher or lower pressure and pressure drop.

With the full impregnation as well as also with the additional impregnation of the trunk end or the like, a further reduction in the impregnation period can be obtained by influencing the viscosity of the protective solution by increasing the temperature and/ or by the addition of suitable chemicals. Similarly, the turbulence may be reduced by means of suitable chemical additions such as polyethylene oxide.

Referring now to the drawings in detail, and FIG. 1 thereof in particular, the cap illustrated therein comprises a cap portion 1 of cylindrical shape which is made of form-retaining material as, for instance, metal strong synthetic material, or the like. The cap furthermore comprises a clamping ring 2 of Wedge or trapezoidalcross-section, and a doublewall sealing sleeve or cuff 3 defining an intermediate space of U-shaped cross-section between the outer wall 7 and the inner wall 6. The cap portion 1 has its marginal area, and more specifically the bottom portion thereof, provided with an annular groove 4 of U-shaped cross-section which is open toward the bottom and serves for an air-tight fitting of the upper open end of sealing sleeve 3 by means of the clamping ring 2. To this end, the cap portion 1 is provided with a plurality of bores 22, whereas the clamping ring 2 carries at its upper portion uniformly distributed stud bolts 5 which, following the insertion of the clamping ring 2 into the opening between the inner wall 6 and outer wall 7 of said sealing sleeve 3 are passed through the bores 22 in the cap portion 1 and are tightened by means of nuts 23. In order to prevent a premature destruction of the upper ends of the walls of the sealing sieeve 3, said upper ends may be provided with a fabric insert. The sealing sleeve 3 is made of rubber with fabric threads or a fabric insert. In each wall, the threads extend only in one inclined direction, in other words, do not cross each other. Furthermore, the threads in the inner wall 6 of the sealing sleeve 3 and the threads in the outer wall 7 of the sealing sleeve 3 have the same inclined direction with regard to the longitudinal central axis of sleeve 3. Only in the zenith portion 9 and its immediate vicinity do the fabric threads of both sleeve walls 6 and 7 cross each other and thus form a double fabric. In this way, this portion of the sleeve 3 is particularly reinforced.

The cap portion 1 carries a connection or fitting 10 for the connection of a hose by means of which the wood protective solution is by a pump pressed from a reservoir into the chamber 11 between the bottom of the cap 1 and the end face 12 of the trunk 13. Furthermore, the clamping ring 2 has a connection or fitting 14 extending through the bottom of cap 1, said connection 14 forming a valve and leading to the bottom side of the clamping ring 2. Reference is made to FIG. 3 to show how connection 14 cooperates with chamber 8. The said connection 14 serves for feeding a liquid or gaseous pressure medium into the chamber 8 of the sealing sleeve 3. To this end, the said connection 14 is connected to a pump which presses the pressure medium into the space 8. Depending on the pressure of the pressure medium, the inner wall 6 of the sealing sleeve 3 is under more or less high force sealingly pressed against the circumferential surface of the trunk end.

, The impregnation of the tree trunk occurs in the followmg manner: First, the trunk end 13 on which the cap is to be mounted is de-barked. Thereupon, the sealing sleeve 3 is pulled over the trunk end 13 into the position shown in FIG. 1. Advantageously, the inner diameter of the sealing sleeve 3 is less than the outer diameter of the trunk end 13, so that the sealing sleeve 3 will engage the trunk end 13 under preload. Thereupon, through the connection or fitting 14 liquid is passed by a pressure pump from a reservoir into the intermediate space 8 or, if desired, air at high pressure is pressed into the intermediate space 8. Due to the position of the fabric threads in the walls 6, 7 in conformity with the present invention, the sealing sleeve 3 is stretched by said pressure in its longitudinal di= rection and has its inner waii 6 firmly pressed in radial direction against the trunk end 13 without the formation of folds. For purposes of protection against damage and to improve the effect, a sleeve 15' of possibly form-retaining material as, for instance, sheet metal, fine synthetic material, or the like, is place over the sealing sleeve 3.

After the said sealing of the cap on the trunk surface has been obtained, the wood protective solution is pressed through the fitting at a high pressure of 2 kp./cm. and more into the space 11 and thereby against the end face 12 of the trunk 13 and penetrates the entire impregnatable portion of the trunk. In order to prevent the cap from slipping off the trunk end, in view of the high pressure of the protective solution, it is necessary to secure said cap to the trunk end 13. This may be effected, for instance, by screwin-g a wood screw through a bore in the bottom of the cap 1 into the end face 12 of the trunk end, thereby securing the cap to the trunk end. As will be evident from FIG. 1, also barbed hooks 16 may be provided as shown in the drawing. In this instance, only one row of barbed hooks may be provided over the inner circumference, but if desired, also a plurality of such rows of barbed hooks may be employed. The impregnating cap may also be secured by providing the inner wall 6 with a plurality of ribs or profile rings protruding inwardly. That surface of the ribs or rings which engages the circumferential surface of the trunk end may be designed, for instance, concave in the manner of a suction cup. Instead of the rings or ribs, also other securing means may be employed.

With the impregnating operation described above, the other trunk end is under atmospheric pressure. However, if desired, it may also be placed under a vacuum. T 0 this end, a cap of the type shown in FIG. 1 may be placed upon the other trunk end and employed as suction cap.

. In this instance, a pressure will be exerted by the protective solution upon one trunk end, whereas a vacuum will be exerted upon the other trunk end. In view of the vacuum, the pressure drop between the two trunk ends, which is already high in view of the pressure at which the protective medium is pressed against one trunk end, will still be further increased which in turn increases the flow velocity of the protective solution in the trunk whereby the impregnating period is further reduced.

Instead of the cap shown in FIG. 1 also a cap illustrated in FIG. 2 may be employed. As will be seen from FIG. 2, the opening or mouth of the rigid cap portion 15 has detachably connected thereto a one-wall sealing sleeve 16. This connection may be effected by means of a hose clamp 17. The sealing sleeve 16 is made of elastic material, especially rubber, or of rubber having inserts therein of fabric threads or fabric. The suction pipe 18 for connection with a suction pump may be centrally or eccentrically mounted on the cap portion 15 which latter may consist of metal or strong synthetic material, or the like.

As will be seen from the drawing, the diameter of the mouth of the rigid cap portion 15 is greater than the diameter of the trunk to be impregnated, whereas the inner diameter of the elastic sealing sleeve 16 is less than the outer diameter of the trunk end 19. With such a design, a total of only four cap sizes is required for trunk diameters of from 12 to 24 centimeters.

The cap is with the sealing sleeve 16 pulled over the trunk end 19. Due to the preload of the sealing sleeve 16 on the circumferential surface of the trunk, no additional holding means is required. In view of the suction during the evacuation of the space 20 between the cap portion 15 and the end face of the trunk end 19, the sealing sleeve 16 is in addition to its preload sealings pressed against the circumferential surface of the trunk end 19.

For purposes of obtaining an increased seal, the diameter of the mouth of the cap portion 15, as indicated in the preferred form of FIG. 2, is dimensioned so large that between its inner side and the circumference of the trunk end 19 there is provided a space 21 which serves for receiving the upper portion of the sealing sleeve 16 which latter during the evacuation is drawn into the said space 6 21 and sealingly engages not only the circumferential surface of the trunk end 19 but also the inside of the mouth of the cap portion 15.

The invention serves primarily for impregnating barkcovered sap-fresh woods but can also be employed with de-barked wood immersed in a solution. The particular advantage, however, lies in the application of the invention to bark-covered sap-fresh wood which can-be impregnated in a simple manner, depending on the type of wood and the length of the tree trunk, in a period of from 3 to 24 hours, while that trunk portion which -is exposed in particular to dangers receives an additional or special impregnation. After a protective solution is in a quantity sufficientfor a full impregnation pressed in the above-described manner into the end face 12 of the trunk end, the supply of the protective solution is turned olf, and subsequently'a solution of the same type but of a stronger concentration or of another type is pressed against the end face 12 if it is desired to apply an additional impregnation to the respective trunk end 13. The time period during which the solution is pressed against the end face 12 depends on the type of wood, the length of the trunk portion additionally to be impregnated, the pressure drop between the two trunk ends, and the quality of the solution.

The time required for a full impregnation as well as for an additional special impregnation is determined in conformity with the formula In this formula 2 stands for the impregnating time in hours, p represents the pressurediiference between the trunk ends in atmospheres above atmospheric pressure,

1 stands for the length of the trunk in meters, 0 is a wood constant depending on the type of the wood amounting, for instance, for firwood approximately to atmospheres above atmospheric pressure It is, of course, to be understood, that the present invention is, by no means, limited to the particular embodiments shown in the drawings and the method set forth above, but also comprises any modifications within the scope of the appended claims.

For the sake of completeness, it may be mentioned that the term kp. as it appears hereinbefore means kilopond and represents the force at which the mass of 1 kilogram presses upon its support.

What we claim is:

1. A cap for use in connection with the impregnation of wood, especially a bark-covered sap-fresh trunk, which comprises: a substantially rigid first section having means for connection with a source of wood impregnating solution and an elastic second section connected to said first section and adapted firmly and tightly to engage the peripheral portion of a trunk to be impregnated so as to form a liquid-tight chamber with said rigid section and the trunk portion adjacent thereto, said second section being detachably connected to said first section and comprising two radially spaced wall portions and an intermediate wall portion interconnecting said two radially spaced wall portions, said three wall portions together defining an annular chamber of U-shaped cross-section provided with means for admitting a pressure fluid to press the inner wall of said annular chamber against the respective adjacent surface of a trunk to be impregnated, said radially spaced wall portions being reinforced with thread means extending in one and the same direction with regard to the axis of said cap.

2. A cap according to claim 1 which comprises a shape maintaining detachable protective cover surrounding said second section. a

3. A cap according to claim 1, in which said intermediate wall portion is reinforced by thread means crossing each other.

4. A cap according to claim 1, which includes a reinforcing fabric band arranged in said intermediate section.

5. A cap according to claim 1, in which the inner diameter of said second section is less than the outer diameter of the trunk upon which the cap is to be placed.

6. A cap according to claim 1, in which said first section has its outer marginal portion provided with an annular groove coaxial with the axis of said first section, and in which said second section has its open portion arranged in said groove, and means arranged within said second section and operable from the outside of said first section for firmly clamping said second section into said groove of said first section. 1

7. A cap according to claim 1, in which said second section is provided with barked means having a portion for engaging the outer peripheral surface of the trunk upon which the cap is to be placed.

8. A cap according to claim 1, in which said second section is provided with corrugated surface means for engagement with a trunk upon which the cap is to be placed.

9. A cap according to claim 1, in which said second section is provided with concave suction surface means for engagement with a trunk on which the cap is to be placed.

10. A cap according to claim 1, in which said second section forms a sealing sleeve of flexible elastic material and in which the inner diameter of said first section adjacent the outer marginal portion thereof is in excess of 8 the outer diameter of the end surface of the trunk upon which the cap is to be placed, said sleeve having an inner diameter less than the outer diameter of the trunk upon which the cap is to be placed.

11. A cap according to claim 10, in which the inner diameter of said first section at the marginal portion thereof is so great as to define an annular chamber with the end portion of the trunk over which the cap is to be placed, said annular chamber being adapted in response to a suction created in said annular chamber to draw a portion of said sleeve into said annular chamber so that a portion of said inner sleeve engages said first section and the oppositely located portion of said inner sleeve engages the trunk upon Which the cap is placed.

12. A cap according to claim 10, in which said first section is provided With a suction pipe adapted to be connected to a source of subatmospheric pressure.

References Cited UNITED STATES PATENTS 708,069 9/1902 PfiStel' 21 68x 735,019 7/1903 PfiStel 2168 1,240,443 2/1917 Hartmann 21-68 1,366,616 9/1919 Wheeler 21 68 2,432,008 12/1947 Hager 21 7X 3,443,881 5/1969 Hudson 11- 7 1,714,701 5/1929 Vannah 117--s9X MORRIS O. WOLK, Primary Examiner S. MARANTZ, Assistant Examiner US. Cl. X.R. 

